Founded in 1909, Harmon County is one of 77 counties in the state of Oklahoma. Historically, Harmon County was formed from Greer County. The city of Hollis is the county seat. With FIPS code of 57, Harmon County has a population of 2,418 and area of 538 square miles (1,393 km2).
List of all cities in Harmon County, OK alphabetically
| City/Town | Postal Code | Area Code |
| Gould, OK | 73544 | 580 |
| Hollis, OK | 73550 | 580 |
| Vinson, OK | 73571 | 580 |